The present invention relates to the provision of an underwater chamber which is capable of being secured in place and is capable of withstanding high compressional forces which are exerted on the chamber by the surrounding environment.
With the recent emphasis placed on obtaining crude oil from the floor of the ocean, research has been pursued for finding a more economical structure to utilize in place of the floating superstructures which are presently mounted extending over the level of the ocean. Attention has recently been directed towards the concept of constructing a concrete pressure vessel for use with sub-sea oil production systems. It has generally been found however, with previously known system that the inability of concrete to carry tension loads can lead to the introduction of surface cracks which in turn enable corrosion, due to migration of the salt water, to occur in the reinforcing steel bars within the composite structure. It has additionally been found that with previously known concrete chambers that it was difficult to reinforce specific places of high stress or point loads within the structure.
The utilization of concrete for providing stability of a superstructure constructed on the open waters has been utilized in various forms, such as illustrated by the U.S. patent to McLean et al, U.S. Pat. No. 2,973,046. In the arrangement illustrated by this patent, a hull filled with concrete is submerged to the floor of the ocean and from this hull a superstructure is constructed extending up out of the water. The utilization of concrete in the structure illustrated by this patent is merely for the purpose of providing sufficient density material for securely mounting the superstructure to the floor of the ocean.
The construction of concrete chambers for underwater use has also been previously attempted, such as illustrated in the U.S. patent to Johnson, U.S. Pat. No. 3,247,672. In the embodiment illustrated by this patent, a concrete chamber is reinforced with steel bars which extend circumferentially through the concrete. Such a chamber however, suffers from the drawbacks noted above especially in that a crack in the concrete will lead to the eventual corrosion of the material.